1. Field of the Invention
This invention relates to a method of recovering gallium from scrap containing gallium.
2. Description of the Prior Art
Gallium is used as a material for making a compound semiconductor such as GaP or GaAs, or as a flux when an epitaxial layer is formed on a semiconductor substrate. As a result, there is eventually formed scrap of a gallium compound or metallic gallium. It is very important to recover gallium from such scrap from the standpoint of effective use of the resources. There are known a number of methods for recovering gallium from scrap. One of them is described in the Japanese Patent Application laid open Under No. 101625/1982. It comprises the vacuum thermal decomposition of scrap containing gallium arsenide, its heating and cooling treatment, filtration of the molten material, treatment for forming an aqueous phase and refining by recrystallization. Another method is described in the Japanese Patent Application laid open under No. 213622/1984. It comprises decomposing an intermetallic gallium compound by oxidation, adjusting the pH of the resulting solution, contacting the solution with a chelate resin so that the resin may adsorb gallium from the solution, passing an aqueous alkali solution through the resin to form an eluate of gallium and subjecting the eluate to electrolysis. Both of these methods are, however, complicated. Moreover, neither of them can recover gallium of high purity easily.